The present invention relates to a novel tire bead supply apparatus for a tire building line, and more particularly to the building of what is called a "green tire".
Generally, a tire building line has a tire building former of generally cylindrical construction whose cylindrical diameter can be selectively expanded or contracted. Rubberized cloth is affixed to the diameter-expanded former to form a cylindrical tire inner layer, thereafter, a ring shaped tire bead, generally made of stranded wire, is set at each of the two ends of the tire inner layer by a bead setter apparatus. Next, such things as a tire outer layer are affixed upon the tire inner layer to complete the building operation of an open-ended, barrel-shaped "green tire". Then, the diameter of the former is contracted to permit removal of the green tire from the former. In a later operation the green tire is cured and given its final, familiar tire shape and tread in a mold under heat and pressure.
This invention relates to the way beads are provided and set at the two ends of the green tire. In one type of conventional bead setter apparatus, the bead setter is in two parts, one part on each side of the former and each capable of holding a bead, the parts also are capable of free axial motion with the center of each bead ring being maintained in alignment with, and the plane of the bead ring being maintained normal to, a central shaft of the former. Generally, the former's central shaft is horizontal and supported at one end while free at the other so that the completed green tire can be slipped off the diameter-contracted former at its free end (See FIG. 1). It is common to call the free end side the "outer" side of the former and the other side the "inner" side of the former. Prior to the green tire building operation, a worker takes two beads from a bead supply peg near the former and engages one bead with a ring-shaped bead holding device ("bead ring") on the outer bead setter and extends the other bead over the former (while the former's diameter is contracted) to engage it with the bead ring of the inner bead setter. Thereafter, he steps on a pedal switch or the like to expand the former's diameter into a smooth drum shape so that the rubber-coated cloth can be affixed to the former's drum-like exterior.
Next the worker steps on a pedal switch or the like causing the inner and outer bead setters to each move towards each other in the axial direction and also towards the centrally located former. This motion of the bead setters towards the respective inner and outer ends of the former brings their respective inner and outer bead rings to positions where the bead rings place their respective inner and outer beads on the drum-shaped rubberized cloth affixed to the former, at places just centrally inwards from the inner and outer ends of the cloth. This leaves a collar-like strip of rubberized cloth beyond the bead at each of the inner and outer ends. Each collar-like strip is next snapped into place up and over its respective bead, usually by an appropriately shaped device, often called a "finger". This completes the bead setting operation, the bead at each end is now snug in the collar fold at that end.
Thereafter, the worker steps on a pedal switch or the like manually and returns the two parts of the bead setter to their original positions away from the former to continue the green tire building operation. When the green tire building operation has been completed, the pedal switch or the like is pedalled to reduce the diameter of the former and the green tire is pulled manually off the former at its free (outer) end.
In the above-described conventional tire molding operation because the amount of the rubber-coated cloth that becomes part of the collar may vary due to differences in rigidity in the rubberized cloth at spliced places (the rubberized cloth is often cut off to a particular width at a particular angle by a bias cutter and the cut end faces spliced together), differences in rubber viscosity, etc. But if the bead position and the amount of rubberized cloth folded up over the bead are not stable, tire size and quality becomes unstable. Also, with the two-part bead setter, prior to the bead-setting operation the worker is burdened with having to manually extend the inner bead over the reduced former to engage it with the inner part's bead ring. Additionally, the worker has to manually pull the completed green tire off the former every time and it is difficult to pull off the green tire keeping its axis parallel to the former's central shaft. Thus, during manual removal the edge of the diameter-reduced former may scratch and damage the green tire's bead portion, affecting its quality.
The present invention is provided to remove such conventional problems. A movable bead setter is disposed between a tire building former and a special automatic bead stocker. The setter is provided with a bead retaining means for concentrically collecting and retaining two beads from the bead stocker, a posture controlling means for controlling the work posture of the retaining means so that the centers and planes of the two beads may be properly aligned with the central shaft of the former, and a translation means or motion controlling means for controlling the motion of the bead setter so that the two beads may also be precisely aligned on opposite sides of the center plane of the former to reduce variation in the bead setting position and amount of the rubberized cloth folded over the beads stabilizing quality and reducing the worker's assembly burden. The form of the invention easily permits addition of a tire retriever means for automatically grasping and removing the completed green tire on the former to reduce the worker's burden and eliminate scratches of the green tire caused by manual retrieval.